Abstract
Integration of a λ derivative into the plasmids having deletions in Tn3 was observed to occur, resulting in a cointegrate or fused molecule of the phage and the plasmid. The cointegrate DNA could be obtained either as phage or as plasmid. The reaction was reversible, giving rise to the original phage and the original plasmid. The integration site of λ was deduced to be a secondary attachment site on Tn3.
